This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The purpose of this pilot study is to evaluate musculoskeletal health (bone strength, muscle size and muscle strength) in young and collegiate hockey and soccer players. We hypothesize that both young and collegiate athletes will have higher bone strength, related to higher muscle mass, at loaded sites compared to controls. This data will be used as pilot data to obtain funding for a longitudinal epidemiological study of musculoskeletal development and injuries in young and collegiate athletes.